217139991264 has 288 divisors, whose sum is σ = 717926017536. Its totient is φ = 60970060800.

The previous prime is 217139991221. The next prime is 217139991307. The reversal of 217139991264 is 462199931712.

It is an interprime number because it is at equal distance from previous prime (217139991221) and next prime (217139991307).

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×217139991264² (a number of 23 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 217139991264.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 65778414 + ... + 65781714.

It is an arithmetic number, because the mean of its divisors is an integer number (2492798672).

Almost surely, 2^217139991264 is an apocalyptic number.

217139991264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217139991264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (358963008768).

217139991264 is an abundant number, since it is smaller than the sum of its proper divisors (500786026272).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217139991264 is a wasteful number, since it uses less digits than its factorization.

217139991264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3878 (or 3867 counting only the distinct ones).

The product of its digits is 1469664, while the sum is 54.

The spelling of 217139991264 in words is "two hundred seventeen billion, one hundred thirty-nine million, nine hundred ninety-one thousand, two hundred sixty-four".